Modified lignin surfactants

ABSTRACT

The improved lignin surfactant of this invention is a lignin modified by reaction with from about 1 to 20 moles, preferably from 2 to 10 moles, per 1000 grams of lignin, of an agent of the type X(CH2)nY, wherein X is a halogen, an activated double bond, an epoxide ring or a halohydrin, Y is a property group such as sulfonate, phosphonate, hydroxyl, sulfide or secondary or tertiary amine, n is an integer from 1 to 5, to at least partially block the acidic hydroxyl groups of the lignin.

AU 115 EX United States Patent [191 Falkehag 1 Feb. 11, 1975 MODIFIED LIGNIN SURFACTANTS Primarv Examiner-Lewis Gotts a [75] Inventor. gtgil Falkehag, Mount Pleasan Assistant Exammer D. R. Phillips Attorney, Agent, or Firm-Richard L. Schmalz; Ernest [73] Assignee: Westvaco Corporation, New York, Lipscomb 1 [22] Filed: Sept. 27, 1973 [57] ABSTRACT [2]] Appl. No.: 401,530 The improved t of this invention is a lignin modified y tr'n with from about I to 20 C r fi f 222 M 25 moles. preferably from 2 to ID moles, per 1000 grams of Ii nin. of an agent pilthe tme M21 1 wherein 1972 X is a halogen, a ri'activafid doub lebond. an epoxide ring or a halohydrimjis a property group such as [221 I(1.8.3! 260/124 A, 8/ij3d7l0flgg fonate' phoSpbOQa-te, hydr Su dc Seco or .I; R ?lry is a rom to 5 to at least [5 e 0 care block the acidic hydroxyl groups of the [56] References Cited UNITED STATES PATENTS 5 Claims. 0 rawings 3,769,272 l0/l973 Hintz 260/!24 R MODIFIED LIGNIN SURFACTANTS CROSS REFERENCE TO RELATED APPLICATION This application is a continuation-in-part of my copending application Ser. No. 256,779, filed May 25, 1972 and now U.S. Pat. No. 3,763,139 granted Oct. 2, 1973.

BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to modified lignin surfactants. More specifically, this invention relates to lignin surfactants that have been modified by blocking the phenolic hydroxyl group.

2. The Prior Art Lignin and sulfonated lignin materials derived from forest products have found widespread use as surfactants, in particular as dispersants and coagulants. Also lignin materials in one form or another are used as drilling mud additives, asphalt emulsifiers, resin extenders and dye dispersants.

Numerous reactants are available to modify lignins in order to improve certain properties, for example, dispersing ability, or to inhibit a property that is undesirable for certain uses, for instance the undesirable dark color of lignin. By way of illustration of methods of modifying lignins the following patents are cited. U.S. Pat. No. 3,600,308 to G. G. Allen describes reacting lignin with a variety of chemical agents to increase molecular weight for use as coagulants. U.S. Pat. No. 3,546,199 to D. T. Christian et al. describes a process for producing polyols from lignin. U.S. Pat. No. 2,854,444 to L. T. Monson et al. describes a process for oxyalkylating lignin sulfonic acid for use as wetting agents and dispersants. The art cited is meant to show the state of the art and is not intended to be all inclusive of lignin modifications.

Although the invention herein described is to new lignin products, it has been found particularly useful as a dispersant for disperse and vat dyes, as cement additives, as metal complexing agents and as a dispersant in general.

It is therefore the general object of this invention to provide a novel alkali lignin or sulfonated lignin surfactant characterized by having the phenolic hydroxyl group blocked. Another object of this invention is to provide a dycstuff composition containing a modified alkali or sulfonated lignin having a blocked phenolic hydroxyl group as a dispersing agent.

Further objects, features and advantages of this invention will be evident from the following detailed description of the invention.

SUMMARY OF THE INVENTION Lignin add ucts comprising the reaction product of an alkali lignin or sulfonated lignin with from about 1 to 20 moles, preferably from 2 to moles per l000 grams of lignin, of an agent of the type X(CH ),.Y, wherein X is a halogen, an activated double bond, such as in acrolein, an epoxide ring or a halohydrin, Y is a property group such as sulfonate, phosphonate, hydroxyl, sulfide or an amine of the types N R, R or N R, R R and R is hydrogen or an alkyl group having up to 18 carbon atoms and n is an integer from I to 5, to at least partially block the acidic hydroxyl group of the lignin. These blocked lignins are useful as surfactants, particularly as dispersants in dyestuff compositions.

DETAILED DESCRIPTION OF THE INVENTION The lignins employed to make the adducts of this invention include alkali lignins from the kraft pulping process and lignins derived from other alkaline pro-.

cesses such as the soda or modified soda processes, sulfonated lignins, such as sulfite lignins from acid and neutral processes and sulfonated alkali lignins. One of the main sources of lignin is the residual pulping liquors of the pulp industry where lignocellulosic materials such as wood, straw, corn stalks, bagasse, and the like are processed to separate the cellulose or pulp from the lignin. For example, the black liquor obtained from the kraft, soda and other alkali processes is not recovered as a sulfonated product but may easily be sulfonated, if desired, by reacting the product with a bisulfite or sulfite. In the sulfite pulping process, the lignocellulosic material is digested with a bisulfite or sulfite to obtain a sulfonated residual pulping liquor wherein the sulfonated lignin is dissolved. Likewise, lignin known as hydrolysis lignin" obtained from the hydrolysis of lignocellulosic materials in manufacturing wood sugars, or hydrotropic lignins" derived from hydrotropic pulping processes may be sulfonated and used.

By the term sulfonated lignin", it is meant any lignin containing at least an effective amount of sulfonate groups to solubilize the lignin in water at neutral or acid conditions. Any of the sulfonated lignins may contain up to one-half of the other materials, such as carbohydrates, phenols and other organic and inorganic compounds. The presence of these other materials results in larger consumption of the reactants used to form the adduct; therefore some purification of the lignin starting materials is often desirable. The nonsulfonated lignin materials may be removed by various known methods. Since the chemical structure of lignin varies according to its source and treatment, the following will be used herein to represent both alkali lignin and sulfonated lignin from whatever source. The degree of sulfonation present in the lignin is not a controlling factor in making the adduct but may be used to tailor the adduct to have desired characteristics.

The lignin materials are reacted with from about i to 20 moles, preferably from 2 to 10 moles, per 1000 grams of lignin, of an agent of the formula wherein X is a halogen, an activated double bond, such as in acroleic, an epoxide ring or a halohydrin, Y is a property group such as sulfonate, phosphonate, hydroxyl, sulfide or an amine of the types N R, R and N R, R R, with R being hydrogen or an alkyl group having up to 18 carbon atoms, n is an integer from 1 to 5, to at least partially block the acidic hydroxyl groups of the lignin. When the starting lignin is a sulfonated lignin, improved dispersing ability begins with just a trace of adduct formation, however, it is preferable to add at least 1 moles of blocking agent. On the other hand, adducts made with alkali lignin need additional blocking, usually at least 1 mole of blocking agent per 1000 grams of lignin to become water soluble. The reaction of lignin with the blocking agent in its salt form may be exemplified wherein the adduct is shown having m as an integer from 0 to 2 depending upon the reactive group X;

The reaction of the lignin with any of the reactants serves primarily to block the acidic hydroxyl groups of the lignin. Depending upon the starting lignin material, whether residual pulping liquors or a refined product, the phenolic hydroxyl content of the lignin can be reduced to substantially zero. The adduct formation, at least to some extent, serves to block other ionizable hydroxyl groups, such as carboxyl and aliphatic hydroxyls. It has been found that by blocking the hydroxyl groups in lignin with one of the agents described herein it is possible to reduce the dark reddish-brown color by l% or more.

Examples of the blocking agents contemplated for the formula X(CH,),.Y when n is 1 include, chloromethane sulfonate, chloromethane phosphonate chloromethanol, chloromethane sulfide, chloromethane dimethylamine and chloromethane didodecylamine. Also, when X is another halogen examples include bromomethane sulfonate, bromomethane phosphonate,

bromethanol, iodomethane sulfonate, iodomethane diethylamine.

When, for example n varies from 2 to 5 included are, chloroethane sulfonate, chloroethane phosphonate, 2- chloroethanol, bromoethane sulfonate, 2- bromoethanol, chloropropane sulfonate, chloropropane phosphonate, 3-chloropropanol, iodopropane sulfonate, iodopropane sulfide, chlorobutane sulfonate, chlorobutane phosphonate, chlorobutanol, chlorobutane sulfide, chloropentane sulfonate, chloropentane phosphonate, chloropentanol.

When Y in the formula is an amine of the type N R R or N R R R the R is an alkyl radical having up to 18 carbon atoms or hydrogen. For example. chloromethane dimethylamine, chloroethane diethylaminc, hromopropane didodecylaminc and so forth.

When X is a halohydrin. say, for example, the halohydrin is 2-chloroethanol and n is the blocking agent in- I eludes compounds of the tyle 3-chloro-2-hydroxy propane-Y property group with the Y group varying. When n is 2 the blocking agent is of the type 4-chloro- 3-hydroxybutane-Y property group and so forth.

When the X is an epoxide ring and n is l, the blocking agent becomes 1,2-epoxypropane-Y property group. In the case wherein n is 2 the blocking agent thus is 1,2-epoxybutane-Y property group. And where X is an active double bond such as in acrolein the blocking agent becomes CHOCHCH CH Y. However, when X is an epoxide the Y group is not intended to include an amine.

The blocked lignins are made by simply dissolving the lignin in water or alkali and intermixing a given amount of blocking agent and reacting at a temperature between about 0C. and 200C. with the time depending upon the temperature used and the degree of blocking desired. The blocked lignin is allowed to cool and then dried. A catalyst, such as sodium hydroxide, may be used if desired but is not necessary.

Blocking the phenolic hydroxyl of lignin with chloromethanesulfonate is highly effective when applied to the phenolic hydroxyl in dry form. It appears 0(CH (CH Y Na that the reaction takes place best at temperatures between l60-l80C. At lower temperatures and in the presence of water the degree of reaction decreases dramatically. Good results were also obtained when lignin was phosphomethylated with chloromethanephosphonate, a chemical commercially available as an aqueous solution. The phosphomethylation of alkali lignin gives products soluble at a pH lower than 1 by reacting 3 moles of chloromethanephosphonate per 1000 grams of lignin with the dry alkaline form of lignin at a temperature of C. However, phosphomethylation already takes place at temperatures down to l00C. to a considerable extent (even during spray-drying) and materials with a precipitation point of about pH 1.85 (at 2% concentration) are produced.

When reacting in a water solution the results are not as good as those obtained from the dry reaction proba bly because of hydrolysis of the chloromethanephosphonate and chloromethanesulfonate at the higher temperatures. The sulfomethylation was found to be as complete as phosphomethylation at temperatures above 160C. but somewhat less complete at lower temperatures.

The surfactants of this invention are particularly useful as dispersants for disperse dyes or vat dyes in either the dry or liquid form. The blocked sulfonated lignins may be added to the dye cake before, during or after grinding. For most dyeing applications an adduct hav ing from 3 to 6 moles of reactant per 1000 grams of lignin starting material is used. It is generally preferred to add the surfactant prior to grinding so that it will be thoroughly mixed and aid in particle size reduction. The amount of blocked sulfonated lignin dispersants added to a dye will vary widely, depending upon the particular dye cake. the material to be dyed and the el' feet desired. Amounts up to 75% of the sulfonated lignin dispersant. based upon the weight of dried disperse or vat dye formulation may be used. The most important factor in determining the proper amount of lignin surfactant to be used in making up the dyestuff is the particular dye cake used. Generally this amount will vary from dye to dye.

Dyestuff compositions comprise, for the most part, a dye cake, i.e., disperse dyes and vat dyes, and a dispersant. These dyestuff compositions are widely used to color both natural and synthetic fibers. The dye dispersants that may be used to disperse the dye cake vary widely in method of manufacture and source. in the dyestuff composition the dispersant serves three basic functions. It assists in reducing the dye particle to a fine size, it maintains a dispersing medium and it is used as an inexpensive diluent. Generally, dye dispersants are of two major types, one of those being sulfonated lignins from the wood pulping industry via the sulfite or kraft process. The disadvantages of sulfonated lignins include fiber staining, reduction of diazo-type dyes, dark brown color and a tendency to stabilize foams.

Fiber staining by the lignin occurs mainly on cellulosic and nitrogenous fibers such as cotton, nylon and wool; polyester fibers are also stained but to a lesser extent. A second disadvantage of sulfonated lignin dispersants has been that when dyeing with diazo-type dyes under high temperature and pressure dyeing processes, the oxidizable lignin structures tend to reduce the diazo dye linkage. Another disadvantage, the brown color, is psychological. Lastly, foam stabilization properties are troublesome for several reasons.

The advantages that water soluble lignin dispersant? possess over other dispersants include the ability to impart better heat stability to the dye dispersion, and to disperse with equal effectiveness. Another advantage ofa water-soluble lignin dispersant is that it tends to act as a dye retarder. Some dyes have a tendency to start dyeing at very low temperatures. Dyers prefer colors to dye a fiber at a steady rate proportional to temperature increase. If the color dyes too rapidly, the goods take on a streaky appearance; and creases in the material dye more rapidly than the face of the cloth.

As stated earlier, these modified water-soluble lignins are particularly useful as dispersants, as cement additives, and as metal complexing agents.

The practice of this invention may clearly be seen in the following examples.

EXAMPLE I Sulfomethylation of Alkali Lignin ln Dry State To 38.7 ml of water 100 grams of alkali lignin was added with stirring. Under a nitrogen blanket 32 grams of (50%) NaOH (4 moles/1000 grams lignin) and 45.7 grams ClCH sQ Na (3 moles/I000 grams lignin) was added at room temperature. Then the material was freeze-dried. 5 grams of this dry material was placed in a 50 ml three neck. round bottom flask, equipped with a condenser, stirrer and an inlet for N and then heated to various temperatures. After 5 hours of stirring. the material was allowed to cool to room temperature. 0.5 grams of each sample was dissolved in 25 ml of water, and HCl (0.5N) was added until precipitation started to occur.

EXAMPLE 3 Phosphomethylation of Alkali Lignin in Dry State To lOO grams of alkali lignin was added 32 grams of 5 a 50% NaOH solution in 387 ml of water with stirring under a N, -atmosphere. After addition of 46 grams clCH PO H [3 moles/1000 grams of lignin] (added as a 85% aqueous solution) and 48 grams 50% NaOH. The mixture was freeze dried. Five grams of this dry lignin sample was placed in a 50 ml. three neck round bottom flask. The material was heated in an oil bath and l gram portions were withdrawn after 15, 30, 60, I and 300 minutes. The products were each dissolved in water (0.5 grams of product in ml of water) and the i5 precipitation point was determined with 0.5 N HCl.

Reaction Time pH After Reaction Precipitation Point Phosphomethylation of Alkali Lignin in Aqueous State Temp (00 pH After Reacnon Preclpmmo" Pom (PH) 100 grams of alkali lignin was added with stirring to 100 1155 5, 387 ml. of water. 32 grams of NaOH 46 g. of {:8 :-gg g g ClCl-l PO H [3 moles/1000 grams of lignin] (85%) 48 160 10:35 (Still in solution) g. NaOH (50%) were added at room temperature I80 10.05 1.0 (still in solution) under an N: atmosphere. 20 ml. of this solution was placed in an autoclave and heated to temperature in an EXAMPLE 2 50 oil bath. After 5 hours of reaction time with occasional Sulfomethylation of Alkali Lignin ln Aqueous State Temp. ("C pH After Reaction Precipitation Point (pH) H10 1 L 6.9 I20 I L35 5.8 140 1!.35 5.9 l ll.30/ll l 5.7/5.5 lBQ I055 5.5

shakings the material was allowed to cool to room temperature. 5 ml of each solution was diluted with 25 ml of water, and HCl (0.5N) was added until precipitation started to occur.

Temp. (C.) pH After Reaction Precipitation Point (pH) l00 ll.65 6.95 60 140 11.50 5.90 I80 l 1.10 5.60

EXAMPLE 5 7 8 Reaction Tim2 P Afle' Reaction PIWiPitatiOH a 50% NaOH solution was added simultaneously at a (Mm') Pom (PH) rate to maintain the pH between 10.5 and 11.0. After 1 Mole 3 hours at 60C. the solution was cooled and the pH 11.40 6.60 was lowered to 9.2 with dilute HCl. The lignin precipig8 2'28 tate was filtered, washed and freeze dried. The nitrogen 60 11.60 2.60 content was 3.07%. 120 11.50 2.55 2 EXAMPLE 8 0 11.35 6.75 5 11.35 2.50 A number of sulfonated llgnlns were treated with the a m2; -g8 blocking agents of this invention and tested as dye dis- 120 10.65 L80 persants. The procedure was to add an aqueous solu- M tion of NaOH and blocking agent to a sulfonated lignin g f-gg dissolved in water with stirring under a nitrogen atmo- 10:85 sphere. After approximately 15 minutes of stirring the 60 10.75 1.30 120 1020 095 15 solutions were dried. The following materials were made for evaluatlon.

Sample Blocking Moles of Add/ Moles NaOH/ Starting No. Additive 1000 grams lignin 1000 grams lignin Material 1 ClCH sO Na 1 None 2 do. 1.5 1.5 Reax 80A 3 do. 3 3 do. 4 do. 6 e do. 5 do. l0 10 do. 6 do. 10 10 Polyfon O 7 ClCH,PO,Na, 1 None Reax 80A 8 do. 15 1.5 do. 9 do. 3 3 do. 10 do. 6 6 do. 11 do. l0 10 do. 12 CICH,CH,OH 6 Polyfon 0 Note: sulfonated Kraft lignin from Westvaco Corporation. "pH maintained at 10.5-11.5 with NaOH.

. EXAMPLE 6 35 Each of these products were evaluated as dye disper- As an example ofa blocking agent wherein X is a hali fil I d ohydrin and the Y property group is a sulfide, 46265 ar lazo lspersa ye was prepare.

. by mixing 5 grams of CI. 21000 (Drsperse Brown 1) 111 grams of epichlorohydrin and 31.0 grams of ethylsuln d w t Th bl k d dd t fide were mixed in the presence of 100 ml. of water to 1 er 0 IS I e 8 6 0c e a 5 form 40 having varying moles of reactant (from 1 mole to 10 moles) were added to the standard dye solution and the dispersing ability, fiber staining. foaming and diazo dye reduction properties measured. The results are shown OH in the table below. 1 The test for determining the extent of fiber staining ClCH -CH-CH -S CH CH caused by lignin based surfactants was to weigh out 10 grams of the lignin based surfactant and dissolve in 300 ml of tap water. Adjust the pH to 9.0 with acetic acid. Add a 5 gram nylon fiber skein and heat to a boil. Boil the mixture for 15 minutes, wash the skein with tap After 3 hours the solution was introduced into a lignin water and dry in an oven at 105C. mixture of 100 grams of sodium lignate (lndulin AT) The test for determining foaming properties of disand 300 ml. of water. The pH was adjusted to l 1.5 and perse dye surfactants was to weigh out 1 gram of sursubsequently heated to 50C. and that temperature factant and dissolve in 100 ml of tap water. Adjust to maintained for 7 hours. The blocked lignin was obpH 9.5 with acetic acid and pour into a 250 ml gradutained after neutralization via freeze drying. The ated cylinder. Rapidly invert 5 times and measure the blocked lignin had no solubility over the entire pH height of the foam in ml immediately after completing range. the inversions and again after 1 minute and 2 minutes have elapsed. If the foam disappears within 2 minutes EXAMPLE 7 note the time at which all the foam vanished. Return To illustrate blocking with an agent wherein X is a the solution after all the foam has broken (or 2 min.) halide and Y is a tertiary amine, 10 grams ofsodium ligand lower the pH to 7.0 with acetic acid and again pernate (lndulin AT) was dispersed in 30 ml of water and form the inversion and recording part of the test. heated under an N atmosphere. A solution of 8.64 The diazo dye reduction test was performed by grams (1(H (H N*((H;,) HCl (6 moles/1000 gram charging a pressure bomb with 500 mg. of C.l. Disperse lignin) in 10 ml of water was prepared and added slowly into the stirring mixture. A separate solution of Brown I dye. 200 cc. water, and 20 grams of sulfonated lignin dispersant. The mixture was thoroughly stirred and the pH adjusted to between S and 6 with acetic acid. A l gram nylon skein was placed in the dye mixwherein X is a halogen. a hulohydrin group. an activated double bond or an epoxide group, Y is it sulfunatc, phosphonate, hydroxyl, sulfide or an amine ol the types N R, R or N R, R R wherein R is hydrogen or an alkyl group having up to 18 carbon atoms, and n is an integer from I to 5, to give lignin adducts having blocked acidic hydroxyl groups.

2. Alkali lignin adducts comprising the reaction prod- Moles Diazo Reactant/ Fiber Foam Test. ml of Foam Run 1000 gms Dye StainpH 7.0 pH 9.5

Lignin Reduction ing lnit. l min. 2 min. lnit. l min I l 5 45 8 (5 2 1.5 4 4 70 5 (50) I5 (3) 3 3 3 3 l3) l5 (3) 4 6 Z l 15 (55) l5 (5) 5 l0 l l (56) l5 (5) 6 l0 3 l 30 l0 (3) 7 l 5 45 6 4 45 l9) 8 1.5 4 5O 7 4 50 10 9 3 3 35 5 (28) 25 I0 6 l-2 40 4 (50) 40 30 ll 10 l 30 (8) 5O 32 l2 6 2 2 30 (i4) Notes: I little or no diazo dye reduction. 5 I severe diazo dye reduction. l little or no fiber staining. 5 severe fiber staining. 25

Numbers in parenthesis represent seconds required for the foam to break.

In all cases the fiber staining and diazo dye reducing tendencies improved when compared with the conventional sulfonated lignin dispersant of Run No. I. Furthermore, good dispersant properties were retained and foaming decreased significantly.

While the invention has been described and illustrated herein by references to various specific materials, procedures and examples, it is understood that the invention is not restricted to the particular materials, combinations of materials, and procedures selected for that purpose. Numerous variations of such details can be employed, as will be appreciated by those skilled in the art.

What is claimed is:

l. Lignin adducts comprising the reaction product of lignin and from about i to 20 moles per 1000 grams of said lignin of an agent of the formula uct of an alkali lignin and from about 1 to 20 moles per 1,000 grams of said alkali lignin of an agent of the formula X UH wherein X is a halogen, a halohydrin group, an activated double bond or an cpoxide group, Y is a sulfonate, phosphonate, hydroxyl, sulfide or an amine of the types N R, R or N R R R wherein R is hydrogen or an alkyl group having up to 18 carbon atoms, and n is an integer from I to 5, to give lignin adducts having blocked acidic hydroxyl groups.

3. The products of claim 2 wherein said alkali lignin is a sulfonated alkali lignin.

4. The products of claim 3 wherein said sulfonated alkali lignin is reacted with from 2 to 10 moles of said agent.

5. The products of claim 2 wherein said alkali lignin is reacted with from 2 to 10 moles of said agent. 

1. LIGNIN ADDUCTS COMPRISING THE REACTION PRODUCT OF LIGNIN AND FROM ABOUT 1 TO 20 MOLES PER 1000 GRAMS OF SAID LIGNIN OF AN AGENT OF THE FORMULA
 2. Alkali lignin adducts comprising the reaction product of an alkali lignin and from about 1 to 20 moles per 1,000 grams of said alkali lignin of an agent of the formula X (CH2)nY wherein X is a halogen, a halohydrin group, an activated double bond or an epoxide group, Y is a sulfonate, phosphonate, hydroxyl, sulfide or an amine of the types N R1 R2 or N R1 R2 R3 wherein R is hydrogen or an alkyl group having up to 18 carbon atoms, and n is an integer from 1 to 5, to give lignin adducts having blocked acidic hydroxyl groups.
 3. The products of claim 2 wherein said alkali lignin is a sulfonated alkali lignin.
 4. The products of claim 3 wherein said sulfonated alkali lignin is reacted with from 2 to 10 moles of said agent.
 5. The products of claim 2 wherein said alkali lignin is reacted with from 2 to 10 moles of said agent. 